CVE-2026-56091
HIGHDescription
When using Apache Shiro with the shiro-guice module in a web servlet context, a specially crafted HTTP request may cause an authentication bypass. This vulnerability is similar to https://www.cve.org/CVERecord?id=CVE-2020-1957 https://www.cve.org/CVERecord , except that it affects the `shiro-guice` module instead of the `shiro-spring` module. This issue affects all Apache Shiro versions through 2.x, and 3.0.0-alpha-1 only when using `shiro-guice` module in a web servlet context. Upgrade to version 3.0.0 or later, which fixes the issue.
How to fix
No published remediation has been found for this vulnerability's affected products yet.
Mitigation guidance may be in the linked vendor advisories in the References section below.
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CVSS v4 Vector
Exploitability
Impact
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:P/AU:Y/R:X/V:D/RE:L/U:Amber
Exploit Intelligence
Low risk: more likely to be exploited than 35% of all known CVEs.
References
Related Vulnerabilities
Other CWE-289 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2024-56511 | Critical | 9.8 | 44% | - | Fix |
| CVE-2021-34746 | Critical | 9.8 | 18% | - | Fix |
| CVE-2017-16590 | High | 8.8 | 3.3% | - | - |
| CVE-2026-48618 | Medium | 6.5 | 3.2% | - | Fix |
| CVE-2025-55130 | Critical | 9.1 | 1.6% | - | Fix |
| CVE-2026-44492 | High | 8.6 | 0.9% | - | Fix |
Common questions
How do I fix CVE-2026-56091?
No published fix for CVE-2026-56091 has been found yet. Check the linked vendor advisories for guidance as it becomes available.
Is CVE-2026-56091 being actively exploited?
Not that we know of. CVE-2026-56091 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.42% is the estimated probability that it will be exploited in the next 30 days. That is higher than 35% of all scored CVEs.
How severe is CVE-2026-56091?
CVE-2026-56091 has a CVSS v4 base score of 8.2, rated high. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
Embed a live status badge for CVE-2026-56091
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-06-25.